Oculary testing chart



M. H. TALLMAN.

OCULARY TESTING CHART.

APPLICATION FILED MAY 1, 1920.

1 412 902, Patented Apr. 18, 1922.

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W I W X 9 S M x 0) I H HXM 2% i-r W jmwzmjmlzzmm earner MALCOLM TALLMAN,OF ASTORIA, NEW YORK.

V OGULARY TESTING CHAR-T.

Specification of Letters Patent.

Patented Apr. 18, 31922.

Application filed May 1, 1920. Serial No. 378,073.'

T 0 all whom it may concern:

Be it known that I, MALcoLM H. TALL- MAN, a citizen of the UnitedStates, and resi dent of Astoria, county of Queens, State of New York,have invented certain new and useful Improvements in Oculary TestingCharts, of which the following is a speciiicat-ion.

One of the objects of my invention is to provide a chart having lettersor characters thereon for testing the acuity of vision which can beviewed and identified either directly or indirectly by reflection.

Another object is to provide a chart having characters or lettersthereon which can be inverted without losing their identity. A furtherobject is to provide a chart having characters thereon which can beeither viewed directly or indirectly by reflection in a mirror andinverted for either direct or indirect observation and yet beidentifiable alphabetic or numerical characters. Other objects will beapparent from the following specification and subjoined claims when readin connection with the accompanying drawings in which Fig. l is a chartillustrating one form of the invention;

Fig. l is a view showing the chart of Fig. 1 as viewed indirectly in amirror;

Fig. 2 is a view of a chart having invertible characters;

Fig. 2 is a view of the chart of Fig. 2 inverted;

Fig. 3 is a view of a chart which can be viewed either directly orindirectly by reflection; inverted, or inverted and viewed indirectly byreflection and in all such cases present identifiable letters ornumerals; as indicated in Figs. 3 3 and 3;

Fig. 4 is a diagram of a testing range.

For testing the vision of a person it is de sirable to have the focaldistance from the ,eyes to the testing chart approximately twenty feet,which necessitates the use of a room over twentyin length for directvision. By use of a mirror M, Fig. i, a much smaller room can be usedand still the long focal distance obtained through reflection, the chartC being placed at the rear of the spectator S as diagrammaticallyillustrated. Heretofore in oculary charts for use with reflectingmirrors it has been the practice to print the letters or characters inreverse formation so that they will present an identifiable characterwhen reflected in a mirror. This necessitates special engraving andtends to make such charts comparatively expensive, and such charts canonly be used in indirect testing by reflection.

My improved chart can be used for either direct or indirect testing asthe characters delineated thereon can be oriented in different wayschanging their perspective value.

The chart of Fig. 1 having the letters thereon can be used for directtesting orfor indirect testing 1n connectlon with a mirror or otherreflector in which case it will appear to the spectator as shown in Fig.1.

In some cases it is advisable to present the letters in different orderto prevent the spectator from memorizing the characters as has been donein examinations of army recruits and railroad men. The chart of Fig. .2serves well for such purposes as it can be inverted so as to appear asshown in Fig. 2 to change the location and order of succession of thecharacters.

A more complex chart is shown in Fig. 3. It can be used for directvisual testing or for indirect testing by reflection in which case itwill a pear to the observer as shown in Fig. 3*. his chart may beinverted as shown in Fig. 3 for direct testing or inverted and used inindirect testing with a reflector in which case the characters willappear to the spectator as shown in Fig. 8.

It will be seen that the characters on the chart of Fig. 1 are allsymmetrical about a vertical axis and therefor do not change theirappearance when viewed in a mirror.

The letters N, S and Z on the chart of Fig. 2 are of such formation thatthey appear substantially the same when inverted as in Fig. 2 theletters H, O and X being symmetrical about a horizontal axis do notchange when inverted. The letters W and M when inverted becomeM and W.

It will be seen that the chart of Fig. 3 includes the letters W and Mwhich are reversible and invertible as above explained. All the otherletters on this chart are symmetrical about both their vertical andhorizontal axes and can therefore be either inverted or viewedindirectly in a mirror without losing their identity.

The characters in the diflerent rows on the charts can be of graduatedsize similar to those illustrated in Figs. 1 and 2, or all substantiallythe same size as in Fig. 3. They may be printed on a plain opaquebackground of a contrasting color or may be coated with a luminousmaterial so as to be visible in a dark room. In some instances they willbe transparent characters on an opaque glass or similar background oropaque characters on a transparent background. It is to be noted thattransparent charts like Fig. 1 and Fig. 3 can be viewed from eithersideas will be apparent by holding the drawing up. to the light with theobverse side toward the spectator. Where transparencies are used a lightmay be placed behind the chart to make the char acters stand out.

Though I have described in detail the embodiments of the inventionshown, it is not to be understood therefrom that I am limited theretoand the above description and the drawings are to be interpreted in anillustrative rather than a limiting sense.

Having thus described my invention what I claim is:

1. A chart for testing the acuity of vision having a plurality of rowsof characters thereon, the characters being alphabetic or numerical onesof such formation that they can be read either directly or indirectly byreflection, said chart being adapted to be inverted so that the order ofsuccession of the characters will be varied.

prising a character or a plurality of characters, and those in each rowbeing of different sizes and of such formation that the chart'can beinverted to vary the order of succession of the characters and yetpresent readable alphabetic letters.

In witness whereof, I have hereunto signed my name.

MALCOLM r1. TALLMAN.

